Heavy Exhaust Fumes on 1999 Toyota Camry

for the past 9 months Ive been smelling
1. Major Exhaust Fumes inside & outside the car.
2. Engine just doesnt sound right it kind of idles high or low or vibrates medium-mild
3. Sucking up gas ,Im getting about 80 miles per full tank of gas.
3. I have used those expensive gas additives about every 6 months.
4.

Your car is running exceptionally rich, it most probably has damaged the catalytic converter having run so rich. Excess fuel burning in the catalytic converter smells bad, perhaps that's the exhaust smell.
The yellow Check Engine Light should be on and will have stored codes indicating what is wrong. Let us know what the stored codes are.